Electric connector with set screw



Dec. 13, 1955' s. N. BUCHANAN ETAL 2,727,220

ELECTRIC CONNECTOR WITH SET SCREW Filed Nov. 15, 1953 2 Sheets-Sheet INV ENTOR. v

If 6 STEPHEN N BUCHANAN j W/LLMM F MCGU/NNESS ATTORNEK 1955 s. N.BUCHANAN EE'AL 2,727,220

ELECTRIC CONNECTOR WITH SET SCREW Filed Nov. 15, 1951 2 Sheets-Sheet 2 IN V EN TOR. STEPHEN N BUCHANAN WILLIAM F MCGU/NNESS A TTORNEK UnitedStates Patent ELECTRIC CONNECTOR WITH SET SCREW Stephen N. Buchanan,Westmoreland Hills, Md., and William F. McGninness, Union, N. J.,assignors to Buchanan Electrical Products Corporation, Hillside, N. 1.,a corporation of New Jersey Application November 15, 1951, Serial No.256,432

4 Claims. (Cl. 339-272) This invention relates generally to electricalequipment and more specifically to an improved connector for electriccurrent carrying conductors.

It is common practice in electrical wiring arrangements to afix aterminal lug on the bared end of an electrical conductor, connect thelug to a block that contains a plurality of spaced terminals, afiix asecond terminal lug on the bared end of a second electrical conductorand connect the second lug to the terminal on the block in order toprovide a continuous flow of current from the first conductor to thesecond. An object of this invention is to provide an improved connectorthat will eliminate this type of connection involving three differentconnecting points by causing the bared ends of the conductors to bemechanically and electrically joined directly together in the connector.

A further object of this invention is to utilize the advantage in lowerelectrical resistance that is afforded by a connection resulting fromdirect engagement of the conductors, as opposed to a connectioninvolving an intermediary element between the conductors, as illustratedabove.

A still further object of this invention is to provide an electricalconnector that includes a movable clamping element permanently attachedto the conductor re ceiving member of the connector.

An additional object of this invention is the provision of an improvedconnector that will mechanically unite two or more electrical conductorsof the same or different commercial sizes.

The illustrated example of the invention includes an open-sided frameheld upright on an anchor through an aperture in the top of the frame. Acap encloses the frame and the screw also passes through an aperture inthe cap, so that the cap and the screw are movable as a unit relative tothe frame. A shoe having a conductor-engaging portion immediately belowthe end of the screw has end portions engaging and held by the cap.Preferably the shoe can rock relative to the cap.

Other objects and advantages will be apparent from the description andthe drawings, in which Fig. l is a perspective view of the screw;

Fig. 2 is a perspective view of an insulation jacket which may be usedto cover the connector;

Pig. 3 is a perspective view of the frame member;

Fig. 4 is a perspective view of the cap member;

Fig. 5 is a view in perspective of the anchor block;

Fig. 6 is a view in perspective of the shoe member before it isassembled with the cap;

Fig. 7 is a perspective view of the locking member;

Fig. 8 is a View in perspective of the screw, frame, cap and shoemembers in assembled form;

Fig. 9 is a side view in section of the assembled conneetor uniting twoconductors;

Fig. 10 is a side view, partly in section, of the assembled connectorwith the insulation jacket inserted there over;

Fig. 11 is a perspective view of the cap member showing the relationshipof the tongues after the clamp screw initially contacts them; and

Fig. 12 is an end view, partly in section, of the connector showingfiller inserted in the bottom of the connector.

Referring to the drawings, reference numeral 10 indicates a frame memberwhich may be formed by bending a metallic strip, of oblong form, into arectangular configuration and joining the ends, short of theirextremities, adjacent the mid-point of one of the sides of the rectangleas shown in Fig. 3. Those portions 12 of the strip between theextremities and the juncture point are provided with notches 14 in theedges thereof. Each notch has a horizontal edge 16, a vertical edge 18extending downward from one end of the horizontal edge, and a third edge29 extending at the other end of the vertical edge and disposed at anangle of approximately with the vertical edge so that the three-sidednotch is irregular in shape. The outer edges of the sides 22 of theframe, adjacent to the side 24 containing the juncture point of the twoend portions, are flared for the more convenient reception of electricalconductors. The other or top side 26 of the frame is provided with anaperture 28 for the reception of a clamp screw 62 to be described later.The inner or confronting surfaces of the sides 22 are provided withthreads 29 that cooperate with the clamp screw. The primary function ofthe frame member in the connector is to receive the various electricalconductors therein and to form a support against which they may becompressed mechanically by the clamp screw so as to afford efiicient andcomplete current flow.

The frame member is supported in upright position, that is preferablywith the longer sides 22 of the frame vertical, on an anchor member 30composed of an insulating material such as laminated Bakelite or thelike in the form of an elongated strip. Spaced at equal distanceslongitudinally on the under side of the anchor member 30 are circularbores 32 extending about one-half the thickness of the anchor member.These bores or openings receive the locking member to be described indetail later. Located on the upper surface of the anchor member in axialalignment with the circular bores are rectangular slots 36, the longdimension of which is equal to the diameter of the circular bore. Theslots 36 in combination with the bores 32 insure that an unobstructedpassageway is formed in the anchor member. The frame member and theanchor member are assembled by placing the notched extremities of theframe member into the rectangular slot so that the under surface of side24 is in contact with the upper surface 38 of the anchor member. Thenotches 14 in the extended portions of the frame member then at leastpartially project into the region defined by the circular bore. Tomaintain the frame member in the anchor member a circular locking member4% is provided. The locking member is preferably metallic with adiameter slightly less than the circular bore 32 in the underside of theanchor member, insuring a snug fit when the lock member is placed in thebore. The lock member has an upright annular flange 42 around theperiphery thereof. Diametrically opposed recesses 44 are provided in theflange for the reception of a tool capable of providing rotary movementto the locking member. Disposed centrally of the locking member is arectangular slot 46 of the same dimensions of the slot in the uppersurface of the anchor member. The sides 48 and 56 of the rectangulariocking member slot 46 contain oppositely disposed cut-out segments 52therein. Each segment has an arcuate edge 54 terminating in a shoulder56. After the frame member has been inserted in the anchor member, thelocking member is placed in the circular bore 32 with the rectangularslot 46 in alignment with the rectangular slot 36 in the anchor memberso that the extended portion of the frame member projects alsobeyond thelocking member. The looking member is then rotatedf90 causing the edgesof the cut-outsegments to. cam upwardly. on theuangular edges thereinseparating the various frame members from .one

another. The end portion of the anchor block may have acircular opening60 extending through the block for the reception of a rivet orbolt'in.order to fasten the anchor block to a support or panel. A counterhore 61isprovided to accommodate the head of the rivet or bolt.

Inorder to insure amechanical and electrical connection betweenconductors placedi-n the frame, a clamp screw62 is provided. The clampscrewispreferably equipped with aconv-entional Phillips head, the underside of which contains serrations 64 in the form of-radial slots, athreaded portion .63, and aportion 65 of reduced diameter. The clampscrew engagesthe threads on the inner confronting su aces of theframe'member as above mentioned. To maintain the clamp screw-62 inengagement with the frame at all times, a Ll-shaped capmember 66 isprovided. The cap member contains in-the'two parallel legs 63, 7t), andnear the extremities thereof, openings 72 for the reception of a shoemember to be later described. in the side 74 of the U-shaped cap memberan aperture 76 is disposed. Also located in the ide 7d are two parallelslots 78, tangential to the aperture 76 and terminating in the legs 68and 70. The parallel slots and aperture define two oppositely disposedlocking tongues 80 upstrucl: from the remainder of cap member 66 asshown in Fig. 4. The tongues have at their unattached extremities acurvature as determined by the curvature of the aperture 76, and arelongitudinally twisted in opposite directions and upstruck from thesurface of the cap member-so that each makes an angle with the side 7 4of the cap member that is supplementary to the angle made by the other.In effect the'tongues form a continuation of a helix which iscomplementary to that on the thread of the clamp screw.

To attain a firm bond between the conductors and the frame member it isnecessary toapply, over as great an area of conductors as possible, aconstant pressure. Therefore a shoe member 82 of particularconfiguration is provided across the open end of the U-shaped cap memberand extending through the frame. The shoe is formed from a metallicstrip and may be considered as composed of two different portions. Thefirst or conductor-engaging portion 84 is bowed so that the undersurface thereof acquires a concave or arcuate configuration. Thespecific type of configuration may be varied depending upon the type andnumbers of conductors to be accommodated in the connector. Theparticular part of the shoe member that lies within the frame member,and this may be considered the approximate middle third part of the shoemember 32, has a length approximately equal to the width of the frame.The other portions of member 32 that overhang the frame are considerablywider so. that not only the bared ends of the conductors are engaged bythe shoe but also that part of the conductors that is protected by theinsulation is also engaged. These latter portions contain grooves 85 inthe conductor- .engat'ing surface so that :1 firm bond between conductorand shoe is il T his arrangement insures a greater resistance to te.sendi forces that act on the conductor as it is flexed when disposed inthe connector. This greater resistance to bending enables the connectorto be utilized in applications where space is a prime consideration andthe conductors of necessity are required to be flexed. ln effect itallows the conductors to be bent around the corners of the connectormore readily than in ihe where the current bearing portionof theconductor alone is engaged by aclamping element. This greatcrresistanceto the bending forcesdue to flexing offers a further advantage in theprolonged expected use of the conductor before mechanical failure isencountered. At each end of shoe member 82 is a portion 86 adapted to bebent back to overlie portion 84, and each portion 36 has a lug 88, lugs88 being adapted to enter openings 72 in the cap member asshown forexample in Fig. 9.

in assembling the clamp screw, cap member and shoe member, theclamp-screw -is first introduced into the cap member byinserting itinthe aperture between the upstruck locking-tongues until the serrations"on the under side of the screw head engage/thelocking tongues. Afterthe serrations move-overxthe inclinedtonguethey will, upon reverse,rotationalmovement, engage or. abut against the elevated side of-theinclined locking tongue and resist such reverse rotational movement.Thereafter the clamp scren and cap member move as a unit with the formerextending about .632 inch below the cap member legs 68,

The clamp screw isthen. threaded through the aperture 28 in the frameso, that movement of. the-screw causes the legs 68, 7b of the cap membertotbe moved downwardly over the openings inthe .framemember. Before thecap and screw members reach the limit .of their downward travel, theshoe member is inserted through the opening in the frame member. Theportions 36 are then bent back over portion 84 and lugs 88 are insertedinto openings 72 in the legs-63, 79 as previouslydescribed so that theclamp. screw-directly engagesthe shoe member. The shoe member, however,engages the cap member only in the openings 72, clearing thelowerextremities of legs and if; by about .032 inch, as pointedout-above. This feature is very importantin that it allows the shoememher to be rockably mounted in the capmember and therefore free toaccommodate conductors. of difierent sizes placed inthe :connector fromopposite directions. For illustration, assume a #l4wire is inserted inthe frame member and a-ir12 wire is'inscrted in the oppositedirection.Formerly when the conductor engaging element was rigidly attached'to theclamp screw, the:larger wire only would receive a firm clamping actionand the possibility always existedthat thc smaller wire-would come free.Under the proposed arrangement as outlined above where theconductor-engagingelementuis capable of a rocking action, constantclamping pressure may be applied on different size conductorsaccommodated in the frame. in practice, it has been found that whentwo-or more condoctors are insertedin the frame, the overhangingportions of the shoe member initially engage the insulation on theconductors. In responseto additional movement of the screw member, themiddle portion of the;shoe.memher tends to flex and contact. the baredends of the conductors located inthe frame, insuring a firm mechanicalbond between the wires and the conductors. As the screw member, capmember and shoe member ,are moved further downwardly on the framemember,by rotation of the screw member, into firm engagement with theelectrical conductors previously-inserted in the frame, additionalrotational force applied to the screw is transmitted through the head ofthe screw to the locking tongues'in thecap member. This additional forceapplied after the shoe member has engaged the conductors tends tomovethe upstruck locking tongues, fulcrumed int-he parallel legs of theU-shaped cap member, inwardly into firm engagement with the reducedshank portion of ,the screw,'insuring a positive lock between the capmember and screw member.

An insulation jacket 96 containing three openings 92, 94 and 9-5 isprovided for use with the connector. The. circular opening 92- in thetop of the jacketallows access to the clamp screw while. the'otheropenings 94 and .96 are aligned so that the conductors may be placed inthe connector. The. jacket is ofuniforrn width but varies as to lengthso as to afford greaterprotection against shock hazard. Assumingthevertical dimension of the jacket is divided into three equal parts,the uppermost third is about as long as the width of the jacket andembraces the upper part of the connector, the lowermost third isconsiderably longer, extending out from the connector in two oppositedirections so that any bared conductor wires that might possibly extendout of the frame in the connector will be enclosed by the jacket. Themiddle third varies in length from the length of the uppermost third tothe length of the lowermost third. Extending across the of the openings94 and 96 is a lip 98 adapted to abut against the vertical side of theanchor block when the sides of the jacket are inserted in theindentations 58. Each indentation may accommodate the two adjoiningsides of ad acent jackets. After the conductors have been inserted intothe insulated connector and clamped therein, lip 98 prevents removal ofthe insulating jacket from the connector. The insulating jacket ispreferably molded from a thermoplastic material but may be composed ofany of the conventional insulation materials used in field installationsof this type. In some applications of th" mproved connector theinsulating jacket may not he required. in such cases a barriercomprising a rectangular shaped strip Bakelite may be inserted in theindentations 58. Additional insulation in the form of a resin idler ionor the like is placed in the bore 32 and allowed to form around thelocking member and that portion of the frame member protruding into thebore. This filler serves to protect these parts of the connector fromdirt and foreign matter as well as insuring against shock hazard. Thefiller also prevents rotation of the locking member in the bore.

When it is desired to use the assembled connector in practice, the clampscrew is moved upward in the frame, moving in unison the cap member andshoe member therewith a distance sufiicient to insert two or moreconductors from a. plurality of different directions. Thismulti-directional approach for the conductors is made possible becausethe conductors may enter the frame member of the connector at an angledue to the flared sides on the frame and the wide portion of the shoemember located outside of the frame, as pointed out above.

Since numerous changes may be made in the abovedescribed constructions,and different embodiments of the invention may be made without departingfrom the spirit and scope thereof, it is intended that all mattercontained in the foregoing description as shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limited sense.

What is claimed:

1. An electric connector comprising a frame having side walls and endportions, one of said end portions having an aperture therein; a screwmovably mounted in said aperture; a conductor engaging shoe, definingwith said side walls and one of the end portions of said frame aconductor accommodating opening, said shoe having enlarged end portionsand a central portion assembled with said frame so that the end portionsprotrude beyond the frame opening, lugs at the extremities of saidenlarged end portions, said lugs being bent back so as to partiallyoverlie said enlarged sections; and a U-shaped cap movably mounted onsaid frame with the parallel legs thereof having aligned openingstherein for the reception of said lugs, said cap including an opening inthe portion connecting the parallel legs for the reception of saidscrew, means for preventing disassembly of said cap and said screwwhereby relative movement of said screw and said shoe is prevented.

2. In an electric connector the combination comprising a frame formedfrom a strip resilient metallic material shaped so as to define agenerally rectangular opening having opposed side walls and endportions, the ends of said strip extending normal to the midpoint of oneof said end portions in a confronting relation so as to form a flange,said flange having notches in the opposed edges thereof, means forclamping conductors in said opening against an end portion of saidframe, a frame support having a passageway therein to accommodate saidflange and a circular recess forming an extension of said passageway,and a lock washer within said circular recess, said lock washer having agenerally rectangular opening, the longer sides of which includediametrically opposed cut out portions terminating in shoulders, saidlock washer being so positioned Within said recess so that the frame maybe inserted through both the passageway and the opening in said lockwasher with the notches in the edges of said frame flange in engagementwith the washer opening whereby the frame may be locked to said supportupon rotation of said washer.

3. An electric connector comprising a frame member having opposed sidewalls and end portions, a conductor engaging shoe movably mounted withinsaid frame, said shoe defining with the side walls and one of the endportions of said frame a conductor accommodating opening, said shoeincluding enlarged portions protruding from said frame and lugs at theextremities of the projecting portions, a screw movably mounted in saidframe and a U-shaped cap mounted on said frame so that the parallelsides thereof enclose said frame opening, said cap including an aperturein one side thereof for the reception of said screw and oppositelydisposed openings in the parallel sides thereof for the reception ofsaid lugs, said last mentioned openings being greater in area than thecross sectional area of said lugs so that limited rotational movement ofthe shoe relative to the cap is permissible.

4. An electric connector comprising a screw having a threaded portiondefining a helix and an unthreaded portion of smaller diameter than saidthreaded portion, an open-sided frame adapted to receive a plurality ofelectric conductors therein and containing an opening in one endthereof, means for mounting said frame on a supporting block, a U-shapedcap having first and second parallel legs and a central portionconnecting said legs and containing a central aperture, first and secondlocking tongues struck from said frame adjacent to said aperture, thefree ends of said tongues at least partially forming the periphery ofsaid aperture, the free ends being twisted relative to the surface ofsaid central portion to define a helix complementary to the helixdefined by the threads of said screw, and a shoe including a centralconductor-engaging portion and first and second capengaging portions atthe extremities of said conductor-engaging portion, the unthreadedportion of said screw being located in said aperture and said threadedportion passing through said opening, so that said legs overlie the opensides of said frame and the conductor-engaging portion of said shoe ispositioned to be engaged by the end of said screw and the cap-engagingportions of said shoe engage said legs.

References Cited in the file of this patent UNITED STATES PATENTS582,464 Dusenbury May 11, 1897 1,437,209 Wenderhold Nov. 28, 19221,514,928 Rabezzana Nov. 11, 1924 2,205,322 Thomas, Jr. et al June 18,1940 2,239,100 Jackson Apr. 22, 1941 2,263,319 Treanor Nov. 18, 19412,287,762 Rogoff June 23, 1942 2,364,846 Hartman Dec. 12, 1944 2,371,446Jensen Mar. 13, 1945 2,401,130 Ayres May 28, 1946 2,542,084 Hrach Feb.20, 1951 2,636,065 Fiske Apr. 12, 1953 2,693,587 Davidson Nov. 2, 1954FOREIGN PATENTS 678,912 Germany July 25, 1939 888,909 France Dec. 27,1943 893,118 France Ian. 17, 1944 905,493 France Dec. 5, 1945

